1. Field of the Invention
The present invention relates to wells, well operations, to methods, apparatus and products for operating wells. In another aspect, the present invention relates to wells, remediated wells, remediation of wells, to methods, apparatus and products for remediating wells, including oil, gas, water, geothermal, or analogous wells.
2. Brief Description of the Related Art
The hard impermeable mass deposited in the annular space in a well by primary cementing processes is subjected to a number of stresses during the lifetime of the well. The pressure inside the casing can increase or decrease as the fluid filling it changes or as additional pressure is applied to the well, such as when the drilling fluid is replaced by a completion fluid or by a fluid used in a stimulation operation. A change of temperature also creates stress in the cement, at least during the transition period before the temperatures of the steel and the cement come into equilibrium. It can become necessary to repair the primary cementing mass.
It is sometimes desirable in production of oil wells to place cement through perforations in the casing of the well both below and above the oil producing formation or zone. This cementing is carried out to prevent water and/or gas from migrating to the wellbore along with the oil. The intent is to leave the water and gas in the formations adjacent to the oil producing zone so that the water and gas will drive the oil to the wellbore, thereby increasing recovery of oil.
Squeeze cementing is a process of forcing a cement composition through perforations, holes or splits in a casing/wellbore annular space of a well in order to repair a primary cement job that failed due to the cement bypassing the mud (channeling); to eliminate water intrusion from above, below or within the hydrocarbon-producing zone; to reduce the producing gas to oil ratio by isolating gas zones from adjacent oil intervals; to repair casing leaks due to a corroded or split pipe; to plug all, or part, of one or more zones in a multizone injection well so as to direct the injection into the desired intervals; and to plug and abandon a depleted or watered-out producing zone.
Due to high pressures involved, squeeze cementing can be accompanied by problems such as propagating fractures. In addition, the use of conventional Portland cement has several potential problems of its own, particularly where high strength and good adhesion to the borehole wall are needed in order to effect good sealing. The presence of drilling mud pockets on channels under the primary cement may not only lead to failure of the primary cement job, but can adversely affect the strength of the squeeze cementing job. In addition, the presence of brine in the well can adversely affect both the primary and remedial cement jobs, increasing setting time and causing loss of strength of the cement.
U.S. Pat. No. 5,178,519, issued Jan. 12, 1993, to Striech et al., discloses a method and apparatus for performing a block squeeze cementing job. The invention provides for perforating the wellbore above and below the desired well formation on a single wireline trip and setting a lower packer on a wireline above the lower perforations. A stinger is positioned in the lower packer, and secondary packer elements on an upper packer are set above the upper perforations. Cementing of the lower perforations is carried out through the lower packer. The secondary packer elements are unset, and the stinger is repositioned adjacent to the upper perforations. Primary packer elements on the upper packer are then set, and the cementing of the upper perforations is carried out through the upper packer and stinger. Setting of the secondary packer elements requires only vertical movement of the tubing string and no rotation. Both cementing steps are carried out on a single tubing trip. The upper packer is retrievable, and the lower packer is of a drillable type. Hydraulic slips may be provided on the upper packer to prevent movement thereof during either cementing operation.
U.S. Pat. No. 6,065,539, issued May 23, 2000 to Noik et al., discloses a method of cementing a casing in a well drilled in the ground comprises injecting a liquid material comprising phenol-formol resin from the surface, wherein the resin is modified by means of a determined amount of furfuryl alcohol, and an amount of mineral filler unreactive towards the resin is added. The invention further relates to a thermosetting cementing material comprising phenol-formol resin. The resin is modified by means of an amount of furfuryl alcohol and comprises at least a proportion of an unreactive granular filler.
U.S. Pat. No. 6,591,909, issued Jul. 15, 2003 to Dao et al., discloses a method and composition is provided using whey protein as a retarder in a cementing composition for use in cementing operations in a subterranean zone penetrated by a well bore.
U.S. Pat. No. 6,767,867, issued Jul. 27, 2004 to Chatterji et al., discloses methods of treating subterranean zones penetrated by well bores in primary well cementing operations, well completion operations, production stimulation treatments and the like. The methods are basically comprised of introducing into the subterranean zone an aqueous well treating fluid comprised of water and a water soluble polymer complex fluid loss control additive.
U.S. Pat. No. 6,899,177, issued May 31, 2005 to Chatterji et al., discloses methods of cementing subterranean zones penetrated by well bores using cement compositions having enhanced compressive strengths are provided. A method of the invention basically comprises the steps of preparing or providing a cement composition having enhanced compressive strength upon setting comprising a hydraulic cement, sufficient water to form a slurry and a hydroxyamine compressive strength enhancing additive. Thereafter, the cement composition is placed in a subterranean zone to be cemented and allowed to set into an impermeable solid mass therein.
In spite of the advances in the prior art, conventional cement systems suffer from a 6 hour safety margin to dump the slurry; long set times; low shear bond values; long cement lengths, and long wait on cement (WOC) times causing high expense.
Thus, there still exists a need in the art for improved methods, apparatus and products for remediating wells.